Why is there talk of a brokered Republican national convention? Because the likelihood of former Sen. Rick Santorum winning the presidency appears lower to most political observers than even that far-fetched and anachronistic possibility.

While former Gov. Sarah Palin distanced herself from the derogatory characterization, she summed up Santorum's electability problem with one phrase: "knuckle-dragging Neanderthal." Santorum's incendiary rhetoric on social issues and "preachy" temperament may appeal to some evangelical conservatives within the Republican Party, but it repulses independent and moderate voters, including women, who may well be decisive in 2012.

Nowhere was this more evident that in his 2006 Senate re-election campaign. Santorum lost to Bob Casey by 18 percentage points, and according to CNN's exit poll from the race, Santorum lost independents by 44 percent, moderates by 30 percent, and women by 22 percent. Unlike many Republicans running that year, there was no scandal tarnishing his name. There was only his public record, which Pennsylvanians found not only unacceptable, but also "hypocritical."

Pennsylvania is not a solidly liberal or wildly unrepresentative state. In fact, Pennsylvania's 2006 midterm electorate was not all that different from the national electorate in 2004. As is typical in midterm elections, it was whiter, wealthier, and more educated. There were fewer conservatives, but about the same number of Republicans. And even though there were more Democrats, the percentage of white evangelicals or born-again Christians in the electorate (25 percent) was slightly higher in the Keystone State that year than in the 2004 presidential election (23 percent). Bush drew 19 percent more support from evangelicals than Santorum, but instructively Bush also garnered 20 percent more support from independents, 10 percent more support from moderates, and 9 percent more from women. Even if Santorum managed to garner similar levels of record-breaking turnout and support from white evangelicals in 2012 as Bush did in 2004, the negative reaction he is likely to engender among independents, moderates, and women would surely sink his candidacy.

Making matters worse, there is no certainty that conservatives will stick by him once they discover what Rep. Ron Paul and former Gov. Mitt Romney call his "liberal" voting record.

All of this is likely why the latest Gallup poll reveals that the majority of Americans, including the majority of Republicans, do not believe Santorum can beat Obama, despite his leading the race for the Republican nomination